package com.p2p.common.utils;

import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * 驼峰法-下划线互转
 * Created by Allen on 2017/4/5.
 */
public final class Underline2Camel {

    private Underline2Camel() {
    }

    /**
     * 下划线转驼峰法
     *
     * @param line       源字符串
     * @param smallCamel 大小驼峰,是否为小驼峰
     * @return 转换后的字符串
     */
    public static String underline2Camel(String line, boolean smallCamel) {
        if (line == null || "".equals(line)) {
            return "";
        }
        StringBuffer sb = new StringBuffer();
        Pattern pattern = Pattern.compile("([A-Za-z\\d]+)(_)?");
        Matcher matcher = pattern.matcher(line);
        while (matcher.find()) {
            String word = matcher.group();
            sb.append(smallCamel && matcher.start() == 0 ? Character.toLowerCase(word.charAt(0)) : Character.toUpperCase(word.charAt(0)));
            int index = word.lastIndexOf('_');
            if (index > 0) {
                sb.append(word.substring(1, index).toLowerCase());
            } else {
                sb.append(word.substring(1).toLowerCase());
            }
        }
        return sb.toString();
    }

    /**
     * 驼峰法转下划线
     *
     * @param line      源字符串
     * @param lowerCase 是否小写
     * @return 转换后的字符串
     */
    public static String camel2Underline(String line, boolean lowerCase) {
        if (line == null || "".equals(line)) {
            return "";
        }
        line = String.valueOf(line.charAt(0)).toUpperCase().concat(line.substring(1));
        StringBuffer sb = new StringBuffer();
        Pattern pattern = Pattern.compile("[A-Z]([a-z\\d]+)?");
        Matcher matcher = pattern.matcher(line);
        while (matcher.find()) {
            String word = matcher.group();
            sb.append(word.toUpperCase());
            sb.append(matcher.end() == line.length() ? "" : "_");
        }
        if (lowerCase) {
            return sb.toString().toLowerCase();
        }
        return sb.toString();
    }

    public static void main(String[] args) {
        System.out.println(underline2Camel("start_time", true));

        System.out.println(camel2Underline("startTime", true));
    }

}

